Some of New Zealand’s older buildings need to be knocked down before another quake does it for us, says Euan Smith Professor of Geophysics at Victoria University’s Institute of Geophysics - and more so because a bigger jolt could be on the way (keep reading).

Professor Smith said the country needed to learn several lessons from the Saturday’s earthquake in Christchurch.

The first lesson, for local authorities and policy makers, concerns what happened to the unreinforced masonry (URM) structures in this earthquake, Professor Smith told the Science Media Centre.

“Engineers in New Zealand have been warning of the danger posed by URM for decades. Some communities have taken action and required property owners to demolish such structures or to take remedial measures, such as retrofitting anti-seismic strengthening, to bring the structures up to an agreed level of performance in expected earthquakes."

The damage to unreinforced masonry structures (URM), including older brick chimneys, was no surprise. The risk had been identified in many studies. For example, chimney collapse was a major contributor to damage to housing in the 1931 earthquake.

10-year deadline"It is time for the rest to act. Owners of unreinforced masonry buildings, and chimneys, everywhere in New Zealand should be given a reasonable period of time - say 10 years - to demolish them or make them safe in future earthquakes.

Action should be taken New Zealand-wide because nowhere is immune from earthquakes that could cause damage to these weak structures, Professor Smith said.

A trigger for a larger quake? Implementing such a policy may be urgent.

"In 1929 there occurred, in west Canterbury, a magnitude 7 earthquake which turned out to be the first of a series of seven major, magnitude greater than 7, earthquakes over the next 13 years," Professor Smith said.

"The series included the second and third largest earthquakes in European times - the M 7.8 Buller and Hawke's Bay earthquakes. The series ended with two M 7.2 and 7.0 earthquakes in the Wairarapa in 1942.

"It is improbable that this occurrence of such large earthquakes in rapid succession was coincidental. It is more likely that the faults which broke during the series were all stressed and ready to break, and that the occurrence of successive earthquakes helped bring forward the occurrence of the next.

"There is no reason to think that such a series could not happen again. Equally there is no way of knowing whether or not Saturday's earthquake has provided a trigger for more large earthquakes in the next few years.

"But if there are other faults that are ready to go, can we risk taking no action on a known and easily remediated peril - URM - and hope that that next earthquake also happens when people are safe in their houses?"

Could have been deathsPolicy makers had only good fortune to thank for the low injury rate on Saturday, and lack of deaths.

“[If the quake had it happened at, say, 12:30pm on a Friday, then the wreckage in the CBD, and damage to and within commercial properties elsewhere, must surely have produced a very much higher casualty rate that would have included deaths,” Professor Smith said.

Easy to say when you aren't an owner of an affected building. It's just another example of cotton-wool-wrapping the whole population to make life risk-free. Cheaper to give all the scaredies a list of all the brick buildings in the country so they could cross trhe road to avoid them - which they'd enjoy doing while they pursed their lips and tut tutted home from the universities et al.

The idea is that the cost of eliminating dangerous buildings would be greater than the cost of doing nothing. Given the costs involved with falling brick (closed companies,deaths) society would be better off spending to eliminate the buildings. Just because it perplexes your simplistic mind doesn't mean its not very sensible. Sigh*

Another diatribe of knee-jerk drivel from an academic.
One of the root causes of the URM problem is the attitude of Councils toward redevelopment, and the prohibitive costs that government legislation and Council bylaws adds to any proposed redevelopment.

Just simple common sense really. The real issue is the cost and the lack of incentives. URM buildings should be penalised via special insurance premiums and should also require signs on front warning of risk. You'd soon see these landlords coughing up to do the work. A lot of lessees probably don't realise the risk and are paying rentals at a level that assume the building is safe and they can continue business should there be an earthquake.

.. as a tenant that's true but you'd be able to claim on your business interruption insurance likewise for landlords on their properties.

On the other hand, reflect the risk of BI and material damage for an URM commensurate with the risk then some of the Landlords would be compelled to do something or go bare. Tenants would be exposed as their insurers would also charge more for BI seeking safer structures or asking for some compensation from landlords for risk...

The replacement work on Newmarket Viaduct in Auckland looks even more sensible now given the improved structural strength of the replacement and recent events.

And for that matter Jon ... as a tenant I'm sure you will be only too happy to contribute to my costs when I, as a property owner, cough up to do the repair/replacement work on my URM properties!!! Can't we bring some common sense back to the debating table and get a little perspective here? Yes it's a tragedy what happened in Christchurch but tragedies happen all over the world and at any time. Does this mean we have to create a cotton wool universe where every conceivable disaster is covered off in advance? If you really think like that why do you get up in the morning? This shouldn't be a "who's to blame" scenario ... let's learn from the tragedy, develop coping mechanisms and recovery plans etc but let's not wrap humanity (or at least our little corner of humanity in NZ anyway) in a bubble of protectionism.

NZ hasnt had an effective policies to entice building owners to strengthen & make safe their masonery & Heritage buildings ! On average it takes 40 years for a building to be strengthened and by that time it has changed hands by up to 7 times or more.

The only way to entice owners to strengthen the 15,000 properties in NZ is by way of Tax breaks ie allow the strengthening and retention of the Heritage Values to be expensed instead of capitalised !

NZ hasnt had an effective policies to entice building owners to strengthen & make safe their masonery & Heritage buildings ! On average it takes 40 years for a building to be strengthened and by that time it has changed hands by up to 7 times or more.

The only way to entice owners to strengthen the 15,000 properties in NZ is by way of Tax breaks ie allow the strengthening and retention of the Heritage Values to be expensed instead of capitalised !